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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Congenital hypothyroidism (CHT) causes severe physical and mental retardation if untreated. If treatment is delayed sequelae of brain damage will persist. The best results will be attained if treatment is started in the first weeks of postnatal life. Most of our patients came to our clinic beyond the age of one year, 45% were older than 5 years. Almost all of them had disturbances in growth and development at the time of diagnosis. Treatment with thyroid hormones resulted in improvement in physical growth, but psycho-social achievements were often very disappointing. In this paper a description of developmental and behavioral disorders of children with CHT before and after years of treatment has been made. Persistent inabilities in speaking, writing and reading, arithmetic and behavioral disorders were found. Some recommendations are given.
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PMID:Developmental and behavioral disorders in children with congenital hypothyroidism. 170 87

Mental retardation caused by congenital deficiency of thyroid hormones can be prevented by early diagnosis and therapy which are assured by neonatal thyroid screening. Congenital hypothyroidism screening is performed in Italy by regional centres which in 1989 have screened more than 82% of neonatal population. Since 1987 a National Register of children affected by CH has been instituted. The results of the analysis of data collected in the first three years are reported.
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PMID:Three years of experience of the congenital hypothyroidism National Register. 172 14

Congenital hypothyroidism (IC) is the most frequent endocrine disease of the infancy and it is caused by primary deficiency of thyroid hormones. The damages derived by protracted hormone deficiency are diffused to all organs and systems and particularly severe for the development of central nervous system. Mental retardation can be prevented by early diagnosis and therapy. Early diagnosis is assured by neonatal thyroid screening performed on all newborns in the first days of life. The progress report on the screening situation in Italy as well as the national coordination realized in this field are presented.
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PMID:[Congenital hypothyroidism: organization and coordination of neonatal screening in Italy]. 175 85

Endemic cretinism is the most severe manifestation of dietary iodine deficiency. Two forms of the syndrome are traditionally described: neurological and myxoedematous. Although this classification highlights the important neurological sequelae of the disorder it implies that myxoedematous cretins have an alternative mechanism. Further, the nature of the neurological deficit associated with both types of endemic cretinism has received scant attention in recent times considering that it remains a common disorder in many parts of the world. The nature and extent of the neurological deficit found in endemic cretinism was investigated in 104 cretins from a predominantly myxoedematous endemia in western China and in 35 cretins from central Java, Indonesia, a predominantly neurological endemia. We found a similar pattern of neurological involvement in nearly all cretins from both endemias, regardless of type (myxoedematous or neurological), and of current thyroid function. Hallmarks of the neurological features included mental retardation, pyramidal signs in a proximal distribution and extrapyramidal signs. Many patients exhibited a characteristic gait. This probably reflected pyramidal and extrapyramidal dysfunction, although joint laxity and deformity were important contributing factors. Other frequently encountered clinical features were squint, deafness, and primitive reflexes. Cerebral computerized tomography (CT) revealed basal ganglia calcification in 15 of 50 subjects. The presence of basal ganglia calcification was confined to cretins with severe hypothyroidism. Otherwise, cerebral CT scanning demonstrated only minor abnormalities which did not contribute to the localization of the clinical deficits. We conclude that the same neurological disorder is present in both types of endemic cretinism reflecting a diffuse insult to the developing fetal nervous system. These clinical findings support the concept of maternal and fetal hypothyroxinaemia, arising from severe iodine deficiency, as the primary pathophysiological event in endemic cretinism. Differences between the two types of cretinism may be explained by continuing postnatal thyroid hormone deficiency in the myxoedematous type, which results in impaired growth, skeletal retardation and sexual immaturity.
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PMID:The neurology of endemic cretinism. A study of two endemias. 204 52

Congenital hypothyroidism is a preventable cause of mental retardation. Since clinical signs of congenital hypothyroidism do not generally become obvious before three months of age, screening programmes have been introduced in North America and Europe, which consist of T4 or TSH screening on newborn infants on the third day of life. The screening for congenital hypothyroidism was initiated in Pakistan by the Aga Khan University Hospital (AKUH) in March 1987. By April 1988, 5000 neonates were screened and five cases of congenital hypothyroidism were diagnosed. The study revealed the incidence of hypothyroidism to be one case per 1000 newborns which is about 4 times more than that in the West.
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PMID:Neonatal screening for congenital hypothyroidism in Pakistan. 251 33

Congenital hypothyroidism is a common but preventable cause of mental retardation. The incidence of congenital hypothyroidism in the newborn population is about 1:3500 to 1:4000. Infants with Down's syndrome are at a special risk. Fort et al. reported an incidence of persistent primary congenital hypothyroidism in infants with Down's syndrome of 1:141 or 28 times higher than the general newborn population. Premature infants have varying degrees of immaturity of hypothalamic-pituitary-thyroid system and are at a special risk for a variety of thyroid disorders. These patients need adequate understanding and interpretation of their laboratory values before institution of replacement hormonal therapy. Screening programs are available in 48 states and have led to prompt diagnosis and recognition of most cases that would otherwise be missed. Prevention of mental retardation depends on early and adequate treatment. This requires close cooperation between the program and the physicians involved in the care of the infant. Many state screening programs maintain a list of experts who are available for consultation, if necessary.
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PMID:Congenital hypothyroidism: diagnosis, treatment, and prognosis. 308 Dec 94

It is well known that insufficient production of thyroid hormones during the fetal and neonatal period of development may result in permanent brain damage unless treatment with thyroid hormone is instituted very soon after birth. But congenital hypothyroidism is not the only situation in which brain damage may be related to insufficient thyroid function. Cretinism is the most severe manifestation of iodine deficiency disorders found in areas where iodine intake is greatly reduced. Some of the manifestations of cretinism suggest that the insult to the developing brain starts earlier than in the case of congenital hypothyroidism. Hypothyroxinemia of mothers with adequate iodine intake may also leave permanent, though less severe, mental retardation. For these reasons the possible role of maternal transfer of thyroid hormones during early fetal development have been reinvestigated, using the rat to obtain various experimental models. It has been shown that thyroid hormones are found in embryonic tissues before onset of fetal thyroid function and that thyroidectomy of the mother results in delayed development of the concepta. The concentrations of T4 and T3 in embryonic tissues from thyroidectomized dams were undetectable before the onset of fetal thyroid function, and still reduced in some tissues near term, despite the onset of fetal thyroid function. Treatment of control and thyroidectomized dams with methyl-mercaptoimidazole to block fetal thyroid function reduced thyroid hormone concentrations in fetal tissues near term, but this decrease could be partially avoided by infusion of physiological doses of thyroxine to the mothers. Iodine deficiency of the mothers resulted in thyroid hormone deficiency of the developing embryo, which was very marked until term in all tissues including the brain. The results strongly support a role of maternal thyroid hormones in fetal thyroid hormone economy both before and after the onset of the fetal thyroid function, at least in the rat. They also support a role of the hypothyroxinemia of iodine-deficient mothers in initiating the brain damage of the endemic cretin, a damage which would not be corrected once the fetal thyroid becomes active, as iodine-deficiency of the fetus would impair adequate production of hormones by its own thyroid, and maternal transfer would continue to be low.
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PMID:Fetal and maternal thyroid hormones. 329 61

Congenital hypothyroidism is a relatively common endocrine disorder, affecting one in 4000 newborn infants. Undiagnosed and untreated congenital hypothyroidism will result in un-toward consequences, including mental retardation and other significant neurologic sequelae. For these reasons, programs to screen newborns were developed to detect congenital hypothyroidism before clinical features become obvious enough to suggest the diagnosis. The most common clinical features include prolonged jaundice, skin mottling, hypotonia, umbilical hernia, constipation, and macroglossia. Congenital hypothyroidism may be caused by several different disorders; ectopic thyroid glands represent the most common cause. There is accumulating evidence that autoimmune thyroid disease as manifested by TBII may be the cause of thyroid dysgenesis in some cases. The diagnosis is easily confirmed by finding a low serum free T4 or total T4 and elevated serum TSH concentration. The treatment of choice is levothyroxine; these infants must be followed carefully to ensure normal growth and development and maintenance of serum T4 and TSH within the normal ranges. With appropriate treatment and follow-up, the large majority of these infants have an excellent prognosis, with an IQ no different from comparison populations. However, it appears that there is still a small percentage of infants who are the most severely affected, who manifest the lowest serum T4 levels, thyroid aplasia, and retarded bone ages, and who may run the highest risk for some degree of retardation and other neurologic sequelae. Acquired hypothyroidism is also a relatively common disorder, occurring in one in 500 to one in 1000 school-age children. These children most commonly have a slowdown in growth, short stature, a goiter, and a drop in school performance. Other clinical features may be subtle or absent except in more severe or long-standing cases. The most common cause is chronic lymphocytic thyroiditis. The diagnosis is easily established by finding low serum-free T4 or total T4 and elevated serum TSH concentrations. Again, levothyroxine is the treatment of choice. With appropriate treatment and follow-up, all clinical features that develop after age 3 should be reversible and the prognosis should therefore be very good.
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PMID:Diagnosis and treatment of hypothyroidism in children. 331 7

Congenital hypothyroidism, if not treated in very early life, severely impairs the neuropsychological development of affected subjects. We have carried out a detailed analysis of cognitive functioning and personality traits in 18 congenital hypothyroid patients treated late and/or unproperly. Significant cognitive defects were observed, the most important being a defective learning ability and an impaired capacity to judge socially significant events and to project complex actions in a temporal perspective. A mental retardation (IQ less than 70) was observed in 8/18 (44.4%) of these patients, a moderate intellective deficit in 5/18 (27.8%) and an IQ greater than 85 in the remaining 5 patients (27.8%). These data indicate that the mental defect of congenital hypothyroid patients may be overestimated. The patients personality was characterized by dependence on the mother, worrying about their body, maladjustment and socialization problems. Since the intellective prognosis of these patients may significantly improve when the environmental conditions are optimized, social and psychological help must always be suggested.
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PMID:Personality traits and mental prognosis in patients with congenital hypothyroidism not treated from early life. 341 Oct 89

Congenital hypothyroidism is the commonest endocrine disorder of childhood. Early thyroxine therapy will ameliorate or prevent the considerable physical and mental retardation that is the hallmark of infantile hypothyroidism, and evidence is presented that a neonatal screening programme for thyroid hormones will reveal evidence of primary thyroid hypofunction (1/4 500 births) in infants prior to clinical diagnosis.
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PMID:Congenital hypothyroidism. Clinicopathological aspects and biochemical screening. 701 10


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